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64

PJLAN  OF MAMMALIAN LIVER

as this. In Phalanger vtK&Gulatus the two sections of the gut arc
as nearly as possible equal in length, while in Phascolarc.tos th<
large intestine is considerably longer than the small, the length;
being respectively 160 inches arid 111 inches. It is comnioi
among the Marsupials and also among the Kodents for thes<
proportions to exist, i.e. for the large intestine to be as long a?
or longer than, the small. But there are so many exception
that no general statements can bo extracted from the facts.

Some few details will be found in the systematic part of till
book. Mr. Chalmers Mitchell has brought forward some reason
for associating a great length of large intestine with an archai
systematic position, in. the birds at any rate. The facts he*
briefly touched upon are not at variance with the extension <
such a view to the mammals.

Appended to the alimentary tract are three glands or sets <
glands. Opening into the mouth cavity are the salivary (/land

wliich arc of eiiormoi
size in Anteaters, ai
small or absent :
Whales. In their iiui
ber and position the
glands are charactc
istic of mammals. In
the intestine opcin t
ducts of the paucn
and liver, two glan
which the manmi;
Mhuro with lower vtvr
,..            . _ . , ,. ,,, , brates. The form

10. 4.2,Diagrammatic plan of the liver of a Mammal

(posterior   surface).      c, Caudate   lobe;   </> cystic   the   I'W&T   IS,
fissure;   dw, ductus venosus ;   ff, g'all - bladder;   lct   p-pri^rjill \r i
left   central   lobe;   U,  left  lateral  lobe ;   {$/; left   fo*'"t'A*w*'j
lateral fissure; p, portal vela entering  tnvnvrf*e   of    XUammaLs.         It
fissure ; re, right central lobe ; r/ right lateral lo\e ;
rlf, light lateral fissure ; $, SpigtiUan lotws ; t*, um-
bilical vein   vcy post-caval vom.    (After Flower
ad Lydekker.)

being  marked by the  insertion,  of the
vestige of the primitive ventral mesentery.    Bach half is
commonly subdivided into central and lateral lobes.     In
to these, two other divisions are often to be wnthe Spige
"! the caudate lobe*    The liver is less divided in. Oetaoea

howtrv

as a rule i
a right and a left h
the lino of divis
umbi lical li j;ftm<m t